What is the most I can put in a Solo 401(k) for 2026?

Up to $24,500 of employee deferrals plus an employer contribution of 20% of net earnings (Schedule C profit minus half of SE tax), with the two together capped at $72,000. If you are 50 or older at the end of 2026 you can add an $8,000 catch-up, or $11,250 if you turn 60, 61, 62 or 63 in 2026 and the plan allows it. The total can't exceed your earned income.

Why is the employer contribution 20% and not 25%?

For a self-employed person, compensation is net earnings minus the contribution itself. IRS Publication 560's Rate Table for Self-Employed converts a 25% plan rate to 20% (0.25 ÷ 1.25) so you can apply it straight to net earnings.

Solo 401(k) or SEP IRA: which lets me contribute more?

The Solo 401(k) allows at least as much and usually more, because it adds employee deferrals on top of the same 20% employer contribution a SEP allows. At $100,000 of profit, for example, the SEP maximum is about $18,587 and the Solo 401(k) maximum is about $43,087. A SEP is simpler to run and can be opened as late as your return's due date, including extensions.

I also contribute to a 401(k) at my day job. Does that change anything?

Yes, for the employee part. The $24,500 elective deferral limit is per person across all plans, so deferrals at your day job reduce what you can defer into the Solo 401(k). The employer contribution from your own business is figured separately. Enter your day-job deferrals in the calculator to see the reduced amount.

When do I have to open the plan and make contributions?

Publication 560 says a qualified plan must be set up by the last day of the tax year to deduct contributions for that year, and deductible contributions can be made up to the return's due date plus extensions. A sole proprietor whose brand-new 401(k) is adopted after year-end can still count employee deferrals for that first year only if they are paid in before the return's due date, without extensions. A SEP IRA can be set up as late as the due date, including extensions.

Does a Solo 401(k) contribution lower my self-employment tax?

No. SE tax is figured on Schedule SE from net profit before this deduction. Pre-tax contributions are deducted on Schedule 1, line 16, which lowers income tax only. The calculator shows that income tax saving, including the smaller QBI deduction that follows.

Can I make Roth contributions to a Solo 401(k)?

Many plans allow designated Roth deferrals. They count toward the same $24,500 and $72,000 limits but are not deductible, so Publication 560's worksheet subtracts them before arriving at the deductible amount. The tax saving in this calculator assumes every dollar is pre-tax.

Do I have to file anything with the IRS for a Solo 401(k)?

A one-participant plan generally has to file Form 5500-EZ once plan assets reach $250,000 or more at the end of the year. Below that it may be exempt from the annual filing. Contributions themselves go on Schedule 1 of your Form 1040.

Can my spouse be in the plan too?

Yes. The IRS describes a one-participant 401(k) as covering a business owner with no employees, or that person and their spouse. A spouse who works in the business has their own deferral and employer limits. This calculator figures one person.

Solo 401(k) Contribution Calculator (2026 Limits, with SEP IRA Comparison)

Find the most you can put into a Solo 401(k) for 2026 from your Schedule C profit: the employee deferral of up to $24,500, the 20% employer contribution, and any catch-up your age allows, up to the $72,000 limit. The calculator follows the IRS Deduction Worksheet for Self-Employed step by step, shows the SEP IRA maximum next to it, and estimates the income tax a pre-tax contribution saves.

IRS Pub 560 worksheetCatch-up for 50+ and 60–63SEP IRA side by sideUpdated for 2026

Your numbers

Live calculation, no button to press.

Net self-employment profit for 2026

Schedule C line 31: revenue minus business expenses.

Your age

Sets the catch-up: $8,000 at 50 and over, $11,250 in the years you turn 60 to 63.

Filing status

State

Filing status and state only change the tax saving, not the contribution limit.

Your 2026 maximum

Updates live as you type.

Tax year 2026

Solo 401(k) maximum

—

Enter your net profit to see your limit.

Employee deferral—

Employer contribution (20% of net earnings)—

Net earnings (profit minus half of SE tax)—

What this saves you

Income tax saved, Solo 401(k)—

Federal plus state income tax, if every dollar is pre-tax. SE tax doesn't change.

Income tax saved, SEP IRA—

Same calculation for the SEP IRA maximum.

To open a Solo 401(k) for 2026 with employee deferrals, set the plan up by December 31. A SEP IRA can be opened as late as your return's due date, including extensions. See your full tax bill with the 1099 tax calculator.

These results are estimates for educational and planning purposes only, not tax, legal, or financial advice. Verify figures with a qualified tax professional before making financial decisions. FreelanceMath disclaims liability for reliance on calculator output. Updated for the 2026 tax year using IRS Publication 560.

Report an error · or email freelancemath.mail@gmail.com

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Choosing between the two plans?

Read SEP IRA vs Solo 401(k) for Freelancers → for limits at every income level, deadlines, paperwork, Roth options and the backdoor Roth catch.

What this calculator does

A Solo 401(k) lets a self-employed person with no employees contribute twice: once as the employee, through elective deferrals of up to $24,500 for 2026, and once as the employer, through a profit-sharing contribution figured from net earnings. This calculator works out both for 2026 using the IRS Deduction Worksheet for Self-Employed from Publication 560, adds any catch-up contribution your age allows, and checks the total against the $72,000 annual limit and against your earned income. It also shows the SEP IRA maximum for the same profit, and how much federal and state income tax a fully pre-tax contribution would save, using the same engine as the 1099 tax calculator.

The contribution is figured from net earnings, which depend on your self-employment tax. The self-employment tax calculator shows that step on its own, and the self-employment tax guide explains it.

How the calculation works

The IRS gives self-employed people a special computation because your contribution itself reduces the compensation it is based on. Publication 560 turns that circular rule into a worksheet. This calculator follows it in order.

Net earnings
Start from Schedule C net profit and subtract the deduction for half of self-employment tax (Schedule 1, line 15). Publication 560 calls the result net earnings from self-employment, step 3 of its worksheet.
Employer contribution at 20%
A plan can contribute up to 25% of compensation. For a self-employed person, compensation is reduced by the contribution itself, so the Rate Table for Self-Employed turns 25% into 20% of net earnings. Compensation above $360,000 doesn't count for 2026.
Employee deferral
Add elective deferrals of up to $24,500 for 2026. That limit is per person, so 401(k) or 403(b) deferrals at another job this year reduce it. Deferrals can't exceed your earned income.
Annual limit and catch-up
Employer contributions plus deferrals can't exceed $72,000 for 2026. Catch-up contributions sit on top: $8,000 if you are 50 or older at the end of the year, or $11,250 in the years you turn 60, 61, 62 or 63, if your plan allows them.
Tax effect
Pre-tax contributions are deducted on Schedule 1, line 16. The calculator runs your federal and state income tax with and without that deduction, including the smaller QBI deduction that follows, and shows the difference.

Numbers used and why

All 2026 dollar limits come from IRS Notice 2025-67 and the IRS announcement IR-2025-111: $24,500 elective deferrals, $72,000 annual additions, $360,000 compensation limit, $8,000 catch-up at 50 and over, and $11,250 for ages 60 to 63.

The 20% figure is not an approximation. Publication 560's Rate Table for Self-Employed lists 0.200000 for a 25% plan, because 0.25 ÷ 1.25 = 0.20. A SEP IRA uses the same table, which is why the SEP maximum is 20% of net earnings too.

When you make deferrals, the worksheet also limits the employer share to half of net earnings after deferrals (step 12). At low profit that keeps the total from exceeding what you earned.

What this calculator does not include

Employees. A Solo 401(k) is for an owner with no employees other than a spouse. If you have eligible employees, the plan must cover them and nondiscrimination testing applies.
Your spouse's contributions. A spouse who works in the business can have their own deferrals and employer share. This calculator covers one person.
S corporation owners. If you pay yourself W-2 wages from your own corporation, the employer share is 25% of those wages, not 20% of net earnings. That case is not modeled.
Designated Roth contributions. Roth deferrals count toward the same limits but are not deductible. The tax saving shown assumes every dollar is pre-tax.
Other plans you sponsor. Having a SEP or another defined contribution plan for the same business in the same year changes the limits.

These calculations are estimates for educational and planning purposes only, not tax, legal, or financial advice. Tax rules change, edge cases exist, and your specific situation may include factors this calculator does not model. Always confirm figures against the current IRS guidance and your own records before filing or making a financial decision, and consult a qualified tax professional, CPA, or enrolled agent for advice tailored to your circumstances.

Worked example

Scenario: Dana is a freelance software developer in Austin, Texas. She is 45, files single, has no employees and no other job, and expects $100,000 of Schedule C net profit for 2026.

Half of SE tax
$100,000 × 0.9235 × 15.3% = $14,130 of SE tax. Half of it is $7,065, deducted on Schedule 1, line 15.
Net earnings
$100,000 - $7,065 = $92,935 (Publication 560 worksheet, step 3).
Employer contribution
20% × $92,935 = $18,587, well under the $360,000 compensation cap.
Employee deferral
Dana has no other 401(k), so she can defer the full $24,500. It fits inside her earned income.
Total
$18,587 + $24,500 = $43,087, below the $72,000 annual limit. A SEP IRA would allow $18,587.
Tax saved
Deducting $43,087 lowers her federal taxable income from $61,468 to $26,999 after the QBI deduction is recomputed, which saves about $5,243 of federal income tax. Texas has no state income tax.

Result summary

Net profit (Schedule C): $100,000
Half of SE tax: $7,065
Net earnings (Pub 560 step 3): $92,935
Employer contribution (20%): $18,587
Employee deferral: $24,500
SEP IRA maximum: $18,587
Solo 401(k) maximum: $43,087

The extra room comes from the employee deferral. At $100,000 of profit, a SEP and a Solo 401(k) allow the same $18,587 as an employer contribution, but only the 401(k) adds the $24,500 deferral on top. SE tax stays at $14,130 either way, because it is figured before this deduction.

Edge cases and gotchas

Low profit: the worksheet trims the employer share

Situation.: A 52-year-old illustrator has $30,000 of net profit, so net earnings are about $27,881.
What changes.: Deferring $24,500 leaves little earned income, so step 12 of the worksheet cuts the employer share to about $1,690 and the catch-up to the same amount. The total equals net earnings, $27,881.
What to do.: Treat the result as a ceiling. A SEP IRA would allow only about $5,576 here, so the 401(k) still wins at low profit.

You also have a 401(k) at a day job

Situation.: A consultant deferred $20,000 into an employer 401(k) this year and runs a side business.
What changes.: The $24,500 deferral limit is per person, so only $4,500 of deferrals are left for the Solo 401(k). The employer share is separate: each unrelated employer's plan has its own $72,000 limit.
What to do.: Enter the day-job deferrals in the calculator. Check your last pay stub of the year for the exact figure.

Turning 60, 61, 62 or 63 this year

Situation.: A freelancer who turns 61 in 2026 wants the higher catch-up.
What changes.: SECURE 2.0 lets a plan allow up to $11,250 of catch-up in those years instead of $8,000. It is optional for the plan.
What to do.: Confirm your plan document allows the higher catch-up before you contribute it.

Setting the plan up late in the year

Situation.: A freelancer reads this in December and has no plan yet.
What changes.: Publication 560 says a qualified plan must be set up by the last day of the year to deduct contributions for that year. It also has a rule for a sole proprietor's brand-new 401(k) adopted after year-end: employee deferrals count for the first plan year only if paid in before the return's due date, without extensions. A SEP IRA can be set up as late as the return's due date, including extensions.
What to do.: If you want the employee deferral, open the plan before December 31. If you miss that, compare the SEP figure.

Common questions

Sources and references

Every limit, rate and deadline on this page comes from IRS and SSA primary sources. The 2026 Publication 560 is not out yet; the 2025 edition's worksheet is used with the 2026 limits from Notice 2025-67.

Publication 560, Retirement Plans for Small Business (2025)Deduction Worksheet for Self-Employed (steps 1-21), Rate Table for Self-Employed (0.200000 for a 25% plan), catch-up rules, set-up and contribution deadlines, SEP rules
Notice 2025-67, 2026 cost-of-living adjustments for retirement plans2026 limits: §415(c) $72,000, §402(g) $24,500, §401(a)(17) $360,000
IR-2025-111: 401(k) limit increases to $24,500 for 20262026 catch-up limits: $8,000 at 50+, $11,250 for ages 60-63
One-participant 401(k) plansWho qualifies (owner, or owner and spouse), employee and employer contributions, per-person deferral limit, Form 5500-EZ at $250,000 of assets
IRS Releases Tax Inflation Adjustments for Tax Year 2026 (Rev. Proc. 2025-32)2026 brackets and standard deductions used for the tax saving
Contribution and Benefit Base (SSA Office of the Chief Actuary)2026 Social Security wage base ($184,500) in the SE tax step

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FreelanceMath provides general financial information for educational purposes only. This is not professional tax, legal, or financial advice. Always verify with a qualified accountant or tax advisor.

Last updated October 25, 2026 · See our Methodology